Abstract

Retinal and choroidal vascular imaging is a key to the better understanding and diagnosis of eye diseases. To achieve comprehensive three-dimensional capillary imaging, we used an enhanced vascular imaging technique, so called adaptive optics optical coherence angiography (AO-OCA). AO-OCA enables in vivo high-resolution and high-contrast micro-vascular imaging by detecting Doppler frequency shifts. Using this technique, the retinal and choroidal vasculatures of healthy subjects were imaged. The results show that both intensity and Doppler power images have sufficient contrast to discriminate almost all vasculatures from the static tissue. However, the choriocapillaris, pre-arterioles, and post-venules in the Sattler layer were more contrasted by the Doppler technique. In conclusion, AO-OCA enables three-dimensional capillary imaging, and is especially useful for the detection of the choriocapillaris and choroidal capillary network.

Figures (7)

(a) Optical design of achromatizer. An yellow arrow indicates the beam direction from the fiber tip to the retina. (b) The chromatic focal shift with the achromatizer (red solid line) and without the achromatizer (green dashed line).

(a) An example of the OCT volume used to evaluate the performance of bulk motion correction. The red box represents the region of interest. The red arrow indicates the slow-scan direction, and the blue arrow indicates the fast-scan direction. (b) The RMS of phase differences for each B-scan. ‘+’ and ‘×’ respectively indicate the RMS obtained with mean and mode motion estimators.

Wide-field en face projections of intensity (left column) and Doppler power (right column) images at different depths of the GCL and IPL ((a) and (b)), IPL/INL boundary ((c) and (d)), INL/OPL boundary ((e) and (f)) and choriocapillaris ((g) and (h)).

Table 2 Summary of scanning protocols. The fractional displacement is the separation between adjacent B-scans with respect to the 1/e2 beam diameter of the probe. The minimum velocity is estimated for an SNR of 20 dB.

Metrics

Table 1

Participants’ characteristics. ID is the subject ID, Sph and Cyl are spherical and cylindrical refractive errors in diopters and L/R indicates the left (L)/right (R) eye.

ID

Sph

Cyl

L/R

Age

Axial eye length

A

−7.3 D

−0.3 D

R

25

26.24 mm

B

−6.6 D

−0.4 D

R

23

27.52 mm

C

−4.0 D

−0.3 D

R

26

25.73 mm

Table 2

Summary of scanning protocols. The fractional displacement is the separation between adjacent B-scans with respect to the 1/e2 beam diameter of the probe. The minimum velocity is estimated for an SNR of 20 dB.

Protocol ID

Image size [pix] (fast × slow)

FOV [degree] (fast × slow)

Speed [vol/s]

Fractional displacement

Min. velocity [mm/s]

Protocol A

256 × 256

1.3 × 1.3

2.8

0.43

0.024

Protocol B

128 × 128

0.65 × 0.65

5.6

0.43

0.033

Protocol C

128 × 128

0.65 × 0.33

5.6

0.22

0.033

Tables (2)

Table 1

Participants’ characteristics. ID is the subject ID, Sph and Cyl are spherical and cylindrical refractive errors in diopters and L/R indicates the left (L)/right (R) eye.

ID

Sph

Cyl

L/R

Age

Axial eye length

A

−7.3 D

−0.3 D

R

25

26.24 mm

B

−6.6 D

−0.4 D

R

23

27.52 mm

C

−4.0 D

−0.3 D

R

26

25.73 mm

Table 2

Summary of scanning protocols. The fractional displacement is the separation between adjacent B-scans with respect to the 1/e2 beam diameter of the probe. The minimum velocity is estimated for an SNR of 20 dB.